Attachment device for use in the implantation of prosthetic ligament

ABSTRACT

An attachment device includes an elongate guide element which is manipulatable between a pulling position in which its longitudinal axis extends generally parallel to the pulling direction and an anchoring position in which its longitudinal axis extends transversely to the pulling direction. A connecting loop of flexible and implantable material is connected, or connectable, at one end to the guide element and at its other end is connectable to one end of the prosthetic ligament to be implanted. The loop is assembled from a fibre bundle of twisted yarn. Connecting apparatus are formed in the guide elements which permit the loop to be connected thereto. Connector structure is provided on the guide elements to permit lines to be connected to the element in order to pull the guide element, and a trailing implantation system connected thereto, through bone tunnels with the guide element orientated so that its longitudinal axis extends generally parallel to the pulling direction until the element emerges from the mount at one end of one of the tunnels, whereby the guide element is manipulatable by the lines so as to overlie the mouth and thereby anchor one end of the implantation system.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention is concerned generally with the implantation of aprosthetic ligament, and in particular with providing an improvedattachment device for use in guiding a prosthetic ligament to a requiredposition within a bone joint, and to anchor one end of the ligament.

2. Present State of the Art

In the implantation of a prosthetic ligament in a bone joint e.g. theknee joint between tibial and femoral components, it is usual to drilltunnels through the bones, and to pull the prosthetic ligament throughthe tunnels until a required position is reached within the joint,followed by suitable anchoring of the ligament against linear movementin either direction. The anchoring may involve use of bone staples orother intrusive fixations, which attach tensile elements (connected toeach end of the ligament) to suitable bone sites adjacent to the mouthsof the bone tunnels.

Prosthetic ligaments can be made of synthetic material, provided that itis of suitable implantable nature, and which may be woven, or autogenoustissue harvested from the patient can be used.

One more recent endoscopic technique which has been developed in ACLreconstruction (anterior cruciate ligament reconstruction), involves useof an attachment device which serves both to guide the implantation ofthe ligament, and to secure one end of the ligament against axialmovement in one direction, but the attachment device is of such aconstruction that it does not need to anchor itself in position byphysical intrusion into the bone.

The attachment device used in the technique provides easy guidance ofthe ligament, by forming the lead element of a trailing implantationsystem, and which passes through the usual drilled-out bone tunnels, andthen upon exiting of the lead element from an upper mouth of one of thetunnels i.e. when it projects upwardly out of the femoral component, asimple manipulation of the device causes it to overlie the mouth of thetunnel, and thereby provide tensile restraint for the ligament end ofthe now implanted ligament to which it is attached.

The attachment device therefore is capable of being manipulated betweena pulling position, in which it has reduced lateral extent relative tothe pulling direction, and to an anchoring position in which it hasmaximum lateral extent relative to the pulling direction.

This known attachment device comprises a small metal bar which is about12 mm in length, 4 mm wide and 1.5 mm in thickness, and has a row offour circular holes extending through it, of which the two outermostholes serve for attachment of two separate pulling sutures, and theinner pair of holes serve to attach the metal bar to the trailingligament via a further set of sutures. The set of pulling sutures istaken first through the lower end of the lowermost bone tunnel in thetibial component and then passes upwardly through the bone tunnel in thefemoral component, and pulls the trailing ligament system behind it. Inpractice only one of the sutures has tension applied to it sufficient topull the metal bar behind it with the bar manipulating itself to take-upthe pulling position of reduced lateral projection, and to be pulledlengthwise through the tunnels. Since the bar orientates itself so thatits longitudinal axis aligns itself with the pulling direction, thediameter of the final passage drilled through the femoral component canbe reduced, compared with the larger diameter of the tunnel which isformed so as to receive the implanted ligament. This final passagetherefore can have a diameter of slightly more only than the maximumtransverse dimension of the bar (4 mm). Upon exiting from the femoralcomponent, the other pulling suture is then operated so as to manipulatethe bar to take-up a transverse position in which its longitudinal axisis generally perpendicular to the passage whereby it can overlie theexit mouth of the small diameter passage. Downward tension applied tothe trailing assembly attached to the bar then anchors the attachmentbar in position in a non-intrusive manner with respect to thesurrounding bone.

The trailing assembly which follows the pulling-through of theattachment bar usually comprises (a) further sutures which are takenthrough the central pair of holes in the bar, and then connectedtogether to complete the formation of a loop by knotting together of theends of the sutures, and (b) the prosthetic ligament which is attachedto the looped sutures in any convenient manner.

In the case of harvested tissue which comprises tendon material andboney material (plugs) attached at each end of the tendon material, thesutures are taken through holes formed in one of the bone plugs and thenknotted to complete the formation of the attachment loop.

This known technique and attachment device is recognised as being auseful advance in the art of ligament implantation, and the presentinvention seeks to further improve this known device and technique, togain further technical advantages which will facilitate the use by asurgeon (in carrying out assembly of an implantation system for aparticular patient), and which also will provide improved manufactureand stocking of an attachment device for use in implantation systems.

OBJECTS AND BRIEF SUMMARY OF THE INVENTION

According to the invention there is provided an attachment device foruse in an implantation system which includes a prosthetic ligament, inorder to guide the ligament to a required position in a bone tunnelformed in a bone joint between two adjacent bones, and to anchor one endof the ligament, said device comprising:

an elongate guide element which is manipulatable between a pullingposition in which its longitudinal axis extends generally parallel tothe pulling direction and an anchoring position in which itslongitudinal axis extends transversely of the pulling direction;

a connecting loop of flexible and implantable material which isconnected, or connectable, at one end to the guide element and at itsother end is connectable to one end of the prosthetic ligament to beimplanted, said loop comprising a cohesive assembly of twistedfilaments;

connecting apertures formed in the guide element which permit the loopto be connected thereto; and,

connecting means provided on the guide element to permit pulling meansto be connected to the element in order to pull the guide element, andtrailing implantation system connected thereto, through the bone tunnelswith the guide element orientated so that its longitudinal axis extendsgenerally parallel to the pulling direction until the element emergesfrom the mouth at one end of one of the tunnels, whereby the guideelement is manipulatable by the pulling means so as to overlie the mouthand thereby anchor one end of the implantation system.

The loop may be pre-formed, and then connected to the guide element.

Alternatively, the loop may be formed simultaneously, by twistingtogether of filaments of a bundle, and also with its connection to theconnecting apertures in the guide element.

The connecting apertures in the guide element may take any suitableform, to permit easy connection of the connecting loop. In one preferredform, the connecting apertures comprise an adjacent pair of holes, witheach hole having an entry slot which allows the loop to be easilyassembled with the guide element by sliding of part of the loop into it.Each entry slot may be generally “funnel-shaped” to facilitate entry ofthe loop material into the aperture, but which will be more resistant topossible unintended withdrawal from the aperture.

The filament fibre bundle making up the loop may comprise a very looselystructured rope or hank type form, so that it forms a recognisable loophaving two opposite return ends joining together two separate runs ofthe loop. This fibre bundle therefore can be easily assembled with theconnection holes in the guide element, by sliding of a run of the bundlethrough the guide slots.

Alternatively, a fibre bundle may be “threaded” through an adjacent pairof holes (forming said connecting apertures) in the guide element, andwith manipulation of the fibre bundle so as to form a continuous loopconnected to the guide element. In this alterative arrangement, entryslots to the adjacent pair of holes are no longer required.

The assembly of the loop bundle can easily be carried out by the surgeonwho is carrying out the ACL restructuring, and if the surgeon decidesthat the length of the connecting loop (for a particular patient)between the guide element and the adjacent end of the prostheticligament requires to be reduced, it is a simple matter to wrap theconnecting loop more than one time around the connecting web in theguide element between the pair of adjacent holes.

This is a distinct advantage, both to the surgeon in carrying out theimplantation, and also from the point of view of manufacture andstocking of a range of pre-formed loop sizes. This is of particularimportance, because the length of the connecting loop will determine theprecise positioning of the leading end of the ligament as it is beingpulled into position, and precise positioning is technically important,since if the ligament end is drawn too high up into the bone tunnel,there may be an insufficient length of ligament trailing behind it, (ortension elements connected to it), to allow reliable fixation at theentry to the bone tunnel in the tibial component. Alternatively, if theleading end of the ligament is located too far down the bone tunnel inthe femoral component, inadequate tissue ingrowth may arise, givingunreliable long term implantation of the ligament.

However, in some circumstances, it may be desirable to providepre-assembled devices (guide element plus already attached connectingloop) and which can be assembled on a mass production basis. Thisobviates the need to “thread” the connecting loop material through theconnecting apertures in the guide element, by the surgeon in theoperating theatre.

This will be particularly applicable when one size of loop isappropriate, or adequate. The pulling means e.g. sutures also may formpart of the pre-formed assembly, if required.

The invention also includes a novel method of carrying out implantationof a prosthetic ligament, using an attachment device as defined above,and optionally with one or more of the preferred aspects thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention will now be described in detail,by way of example only, with reference to the accompanying drawings, inwhich:

FIG. 1 is a schematic illustration of the femoral and tibial componentsof a knee joint, in which ACL reconstruction is to take place;

FIG. 2 is a schematic and enlarged view of an implantation systemembodying the invention, and intended to be pulled through the bonetunnels formed in the knee joint components shown in FIG. 1, to implanta prosthetic ligament and anchor it therein;

FIG. 3 is a schematic view, showing implantation of a prostheticligament;

FIG. 4 is a plan view, to a considerably enlarged scale, of a guideelement of an attachment device according to the invention;

FIG. 5 is a plan view of a pre-formed connecting loop which can beconnected to the guide element shown in FIG. 4, to form part of animplantation system;

FIG. 6 is a schematic and greatly enlarged view of the implantationsystem, comprising the guide element of FIG. 4, the connecting loop ofFIG. 5, an attached prosthetic ligament, and pulling means attached tothe guide element to pull the entire implantation system through thebone tunnels for implantation;

FIG. 7 is a schematic view of a pre-formed assembly according to theinvention (guide element plus already attached connecting loop) readyfor use by a surgeon;

FIG. 8 is a schematic view of a modification of the guide element shownin FIG. 4;

FIG. 9 is an exploded view of a modified pulling arrangement;

FIG. 10 is a schematic plan view of an alternative construction of guideelement, in the form of a metal bar having four holes, comprising anouter pair for connection to two separate pulling means, and an innerpair to which a connecting loop can be coupled;

FIG. 11 is a schematic side view of the guide element shown in FIG. 10,and having pulling means connected to the outer pair of holes, and aconnecting loop coupled with the inner pair of holes;

FIG. 12 is a plan view of a further arrangement of a pre-formedconnecting loop which can be connected to the guide element shown inFIGS. 4 or 10; and

FIG. 13 is a cross section taken on the line 13—13 in FIG. 12, showingthe twisted together filamental yarns making up the looped fibre bundleshown in FIG. 12.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring first to FIG. 1 of the drawings, there is shown a typical typeof bone joint with which the invention may be used, and which comprisesa knee joint 10 which comprises tibial component 11 and femoralcomponent 12. Enlarged bone tunnels 13 and 14 are drilled through thecomponents 11 and 12, and in which a prosthetic ligament is to beimplanted, but it will be noted that the bone tunnel 14 merges into apassage 15 of smaller diameter, the purpose of which will be explainedin more detail below.

The described embodiment of the invention provides an attachment devicefor use in an implantation system which includes a prosthetic ligament,and which serves to guide the ligament to a required position i n a bonetunnel formed in a bone joint between two adjacent bones, and alsoserves to anchor the leading end of the ligament.

An implantation system is shown schematically in FIG. 2, and comprises aguide element 16 which is generally elongate, having a major axis and aminor axis, and which is manipulatable between a pulling position inwhich its longitudinal axis or major axis extends generally parallel tothe pulling direction (as shown in FIG. 2), and an anchoring position inwhich its longitudinal axis extends transversely of the pullingdirection.

A pre-formed connecting loop 17 is connected at one end 18 to the guideelement 16, and is connected at its opposite end 19 to a leading end 20of a prosthetic ligament designated generally by reference 21.Prosthetic ligament 21 may be a woven synthetic material ligament, ormay comprise autogenous tissue harvested from the patient.

The leading portion of the implantation system comprises pulling means22, connected to the guide element 16, and the trailing end of thesystem comprises tensile elements 23 connected to the trailing end 24 ofthe ligament 21.

The implantation system is shown only schematically in FIG. 2, and theconstruction, and means of interconnecting the component parts of thesystem will be described in more detail below and also shown in moredetail in FIGS. 3 to 6 of the drawings.

FIG. 3 shows part of the implantation system anchored in position in thefemoral component 12.

The guide element is shown to a greatly enlarged scale in FIG. 4, andcomprises a metal bar or strip, designated generally by reference 25. Ithas a pair of connecting apertures 26, and which permit the pre-formedloop, shown in FIG. 5, and designated generally by reference 27, to beconnected to the guide element 25 in its already looped form. The loop27 therefore can be produced by mass production techniques, andcomprises a loosely structured fibre bundle or hank, comprising slightlytwisted monofilamentary yarns. As shown in FIG. 5, the loop 27 is formedfrom a single yarn, formed into continuous loop, and in which the bundleis maintained in its shape, i.e. two opposed runs 28 and return ends 29by means of simple ties 30.

The runs 28 and 29 of the loop 27 can readily be connected to the guideelement 25 by sliding the runs through entrance slots 31 leading to theholes 26. The slots 31 are angled in such a way as to allow easymanipulation by the surgeon, who completes the assembly for a particularpatient, and if the distance between the leading end 20 of the ligament21 from tire guide element 16 is to be changed, it is a simple matter toachieve this, using a standard size of loop 27, by wrapping it one ormore times around the web 32 of the element 25 between the holes 26.

Connection means are also provided on the guide element 25 (not shown)to permit pulling means 22 to be connected thereto, and in one preferredarrangement the connection means may actually be formed by the holes 26.However, alternative means may be provided, e.g. connection eyes or thelike. The pulling means 22 can be operated to pull the guide elements 25and the trailing implantation system connected thereto, through thebones tunnels 13 and 14, and the guide element 25 orientates itself sothat its longitudinal axis extends parallel to the axes of the tunnels13 and 14 and in the pulling direction, so that it presents minimumlateral projection from this axis. The metal bar forming the guideelement 25 typically may have a length of 10 mm, a width of 3 mm, and athickness of 1 mm. The final passage 15 in the femoral component 12 istherefore slightly larger in diameter than the transverse dimension ofthe guide element, thereby allowing the pulling means 22 to pull theguide element 16 (bar 25) through bone tunnel 14 and narrow passage 15,and then emerging from the mouth 33. FIG. 3 shows the bar 25, after ithas been manipulated to a transversely extending position in which itoverlies the mouth 33, and thereby provides anchorage for the leadingend 20 of the ligament 21.

The pulling means 22 comprises a pair of pulling sutures, andconveniently each suture is connected to a respective hole 26, and theseare pulled through the bone tunnels, and then one of these is used asthe main pulling suture to pull the implantation system behind it untilsuch time as the bar 25 emerges from the mouth 33. The other pullingsuture can then be pulled in order to manipulate the bar 25 to take-upthe anchoring position.

FIG. 6 is an enlarged view of the implantation system, and showing theposition taken-up by the bar 25 when in the anchoring position.

By providing the means whereby the effective length of the loop 27 canbe changed, by wrapping turns more than once around the web 32, as shownby dotted lines in FIG. 6, a small number of different size loops 17 canbe manufactured, and supplied to the surgeon, and who can cover a rangeof possibilities with each particular loop that he selects, to meetpatient requirements. In this respect, having reference to FIG. 3, thedistance a (the length of narrow passage 15) and the length of bonetunnel 14, represented by reference b, will vary from patient topatient, and it is desirable that the leading end 20 of the ligament 21should be located about a minimum of 20 mm from the lower end of thetunnel 14, and the effective length of the loop 27 therefore can readilybe adjusted accordingly. Manufacture only of a small range of standardloops can take place, and which can be adjusted to suit differentpatient requirements at the discretion of the surgeon, who can easilyadjust the system to suit particular requirements.

The loop 27 is a fibre bundle or hank, comprising, in a typical case, 96mono filaments very loosely twisted together to form a single yarn i.e.at about 48 turns per meter, and which is formed with overlapping loopedportions which are held together in a loosely structured fibre bundle byties 30, as shown in FIG. 5.

Various alternative embodiments are shown in FIGS. 7, 8 and 9, whichwill now be described.

FIG. 7 shows a schematic view of an already pre-formed assemblyaccording to the invention, comprising guide element 25 a plus alreadyattached connecting loop 17 a, ready for use by a surgeon. This can beassembled on a mass production basis, and obviates the need to “thread”the connecting loop material through the connecting apertures in theguide element, which will be carried out by the surgeon in the operatingtheatre in respect of the embodiment shown in FIG. 4.

FIG. 8 shows a modified arrangement of entry slot to the connectingapertures 26, in which funnel-shaped entry slots 31 a facilitate entryof the loop material into the apertures 26, but which will be moreresistant to possible unintended withdrawal from the apertures.

FIG. 9 shows a modified pulling arrangement, in which pulling sutures 22b may have a large knot or other enlargement 22 c at one end, wherebyupon introduction of the suture 22 b into the aperture 26, followed bytightening, the knot or enlargement 22 c overlies the aperture 26 andprovides tensile restraint against pulling force applied to the suture22 b. One or preferably a pair of such modified pulling means may beprovided.

Referring now to FIGS. 10 and 11, this shows a further construction ofguide element which may. be used in an embodiment of the invention. Theguide element is designated generally by reference 125, and has an innerpair of holes 126 and an outer pair of holes 127. As shown in FIG. 11,pulling means 128 is attached to each of the outer holes 127, and whichfunction in a generally similar manner to the pulling means 22 referredto earlier. FIG. 11 also shows part of a connecting loop 129, and whichis connected to the central pair of apertures 126. Loop 129 can be apre-formed loop, or may be formed by twisting together multi-filamentyarns, which are formed simultaneously with the threading of the fibrebundle through the apertures 126. The loop 129 serves for attachment ofa prosthetic ligament, as described earlier.

One example of the way in which loop 129 can be formed will now bedescribed with reference to FIGS. 12 and 13. A continuous loop 129 isformed, as shown in FIG. 12, and which is derived from twisting togetherof mono-filaments, eg 96 filaments, to form a single yarn, and in arelatively lightly twisted manner. The yarn is then formed into a numberof looped portions e.g. twenty or forty “ends”, which are simultaneouslytwisted together to form a cohesive looped bundle. However, by virtue ofthe “spinning” process involved, a cohesive looped structure is formed,which does not require additional means to maintain the integrity of theloop form, eg does not require the provision of separate ties 30 asdescribed above with reference to FIG. 5. The twisting together of thefilaments, and of the looped portions of the yarn is sufficient to forma cohesive structure, which maintains its looped form.

The looped bundle 129 is preferably formed simultaneously with thepassage of the bundle components through the apertures 126. This may beachieved by any suitable spinning technique.

The looped bundle 129 is derived from a single yarn formed fromtwisted-together mono filaments, of which one run is shown by referencenumeral 130 in FIG. 13. The yarn is formed into a series of overlappinglooped runs 130, e.g. twenty as shown in FIG. 13, and these runs arealso twisted together to form a cohesive fibre bundle.

What is claimed is:
 1. An attachment device for use with a prostheticligament, the attachment device comprising: (a) an elongate guideelement extending between opposing ends and bounding a first connectingaperture and a spaced apart second connecting aperture, the first andsecond connecting apertures being separated by a web portion; (b) firstand second lines connected at corresponding opposing ends of the guideelement; and (c) a connecting loop comprised of flexible and implantablematerial, the connecting loop being looped through the first and secondconnecting apertures so as to be supported by the web portion, theconnecting loop being configured for attachment to the prostheticligament, at least one of said first and second lines being configuredto facilitate selective pulling of the guide element and prostheticligament through tunnels formed in the bone until said guide elementexits one of said tunnels whereby said guide element is manipulated bysaid lines to overlie an opening of the tunnel, thereby anchoring saidguide and ligament to the bone.
 2. An attachment device as recited inclaim 1, wherein the connecting loop is comprised of a plurality oftwisted filaments.
 3. An attachment device as recited in claim 1,wherein the connecting loop is comprised of an elongated coiledfilament.
 4. An attachment device as recited in claim 1, in which theconnecting loop is formed from a single yarn comprised oftwisted-together monofilaments, and in which the single yarn forms anassembly of looped portions which are twisted together to form acohesive loop.
 5. An attachment device as recited in claim 1, in whichthe connecting loop is formed from a single yarn comprised oftwisted-together filaments, and in which the single yarn forms anassembly of looped portions maintained in looped form by ties wrappedaround the assembled portions.
 6. An attachment device as recited inclaim 1, further comprising a first entry slot extending through theguide element and communicating with the first connecting aperture and asecond entry slot extending through the guide element and communicatingwith the second connecting aperture.
 7. An attachment device as recitedin claim 6, wherein the guide element has a first side edge and anopposing second side edge each longitudinally extending between theopposing ends of the guide, the first and second entry slot eachextending through the first side edge.
 8. An attachment device asrecited in claim 6, wherein the guide element has a first side edge andan opposing second side edge each longitudinally extending between theopposing ends of the guide element, the first entry slot extendingthrough the first side edge and the second entry slot extending throughthe second side edge.
 9. An attachment device as recited in claim 1,further comprising a hole positioned at each opposing end of the guideelement, the first and second line each being feed through acorresponding hole for attachment to the guide element.
 10. Anattachment device as recited in claim 1, wherein the first and secondline are each comprised of a suture material.
 11. An attachment deviceto be used as a guide and an anchor for a prosthetic ligament, saidattachment device comprising: an elongated guide element defining alongitudinal axis, said guide element capable of being manipulatedbetween a pulling orientation where said longitudinal axis extendsgenerally parallel to a pulling direction and an anchoring orientationthat is generally transverse to the pulling direction; connectingapertures formed in said guide element; a connecting loop comprising acohesive assembly of twisted filaments, said loop having one endattached to said connecting apertures and an opposite end attachable tothe prosthetic ligament; pulling means connected to said guide elementfor pulling the guide element in said pulling orientation and prostheticligament through tunnels formed in the bone until said guide elementexits one of said tunnels whereby said guide element is manipulated bysaid pulling means to overlie an opening of the tunnel thereby anchoringsaid guide and ligament to the bone.
 12. An attachment device accordingto claim 11, in which the connecting apertures comprise an adjacent pairof holes having a web disposed therebetween, each hole having an entryslot which allows the connecting loop to be assembled with the guideelement by sliding part of the connecting loop into each entry slot. 13.An attachment device according to claim 12, in which the connecting loopis preformed and then connected to the guide element.
 14. An attachmentdevice according to claim 12, in which each entry slot has a taperedconfiguration beginning from said apertures and widening outwardly. 15.An attachment device according to claim 11, wherein said connecting loopcomprises an elongated piece of rope or hank having opposing ends, theelongated piece of rope or hank being looped into a continuous loop andsecured in the continuous loop by ties.
 16. An attachment deviceaccording to claim 15, wherein the connecting loop comprises theelongated piece of rope or hank being looped into at least two loops.17. An attachment device according to claim 12, wherein the continuousloop is looped around the web extending between the holes of theconnecting apertures so that the connecting loop passes through each ofthe holes at least twice.
 18. An attachment device according to claim11, wherein the elongated guide element has opposing ends, the pullingmeans comprising a suture connected to one of the opposing ends of theguide element.
 19. An attachment device according to claim 18, whereinthe suture is connected to one of the opposing ends of the guide elementby looping through one of the connecting apertures.
 20. An attachmentdevice according to claim 11, in which the connecting loop is formedfrom a single yarn comprised of twisted-together monofilaments, and inwhich the single yarn forms an assembly of looped portions which aretwisted together to form a cohesive loop.
 21. An attachment deviceaccording to claim 11, in which the connecting loop is formed from asingle yarn comprised of twisted-together filaments, and in which thesingle yarn forms an assembly of looped portions maintained in loopedform by ties wrapped around the assembled portions.